Light-emitting element wafer, light emitting element, electronic apparatus, and method of producing light-emitting element wafer

ABSTRACT

A light-emitting element wafer including a supporting substrate, a luminescent layer that is formed of a semiconductor and has a first surface and a second surface, the first surface including a first electrode, the second surface including a second electrode, the second surface being arranged between the supporting substrate and the first surface, a junction layer that joins luminescent layer to the supporting substrate and is arranged between the supporting substrate and the second surface, a first inorganic film formed on the first surface, a second inorganic film formed between the junction layer and the second surface, an isolation trench portion that isolates elements and is formed to have a depth such that the isolation trench portion extends from the first inorganic film to the supporting substrate, and a third inorganic film that connects the first inorganic film and the second inorganic film.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/240,266 filed Aug. 18, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/294,264 filed Jun. 3, 2014, now U.S. Pat. No.9,461,197 issued Oct. 4, 2016, the entireties of which are incorporatedherein by reference to the extent permitted by law. This applicationclaims the benefit of Japanese Priority Patent Application JP2013-121462 filed Jun. 10, 2013, the entire contents of which areincorporated herein by reference.

BACKGROUND

The present disclosure relates to a light-emitting element waferincluding a semiconductor material, a method of producing thelight-emitting element wafer, a light emitting element, and anelectronic apparatus using the light emitting element.

A light emitting element that includes a luminescent layer having alaminated structure has been known. In recent years, such a lightemitting element is produced as a light-emitting element wafer in whicha plurality of light emitting elements are arranged from a viewpoint ofreducing the size of the element structure and improving theproductivity (see Japanese Patent Application Laid-open No.2008-172040). Specifically, by causing crystal growth of a luminescentlayer on a wafer and forming an element isolation trench on theluminescent layer with a reactive ion etching (RIE) method, a pluralityof light emitting elements are formed on the wafer. After that, eachlight emitting element is isolated from the wafer, and is mounted on anelectronic apparatus such as a display apparatus and a lightingapparatus.

SUMMARY

In the method of producing a light-emitting element wafer described inJapanese Patent Application Laid-open No. 2008-172040, the depth of theelement isolation trench is significantly affected by the etching rate.Here, it is desirable to use a wafer having a larger area from aviewpoint of mass production. However, it is difficult to obtain auniform etching rate in a wafer surface as the area of the waferincreases. Therefore, in the case where a wafer having a large area isused, it is difficult to obtain a uniform depth of the element isolationtrench in the wafer surface and the height of each element on the waferis non-uniform, which may affect an electronic apparatus after the waferis mounted on the electronic apparatus.

Furthermore, in each light emitting element described in Japanese PatentApplication Laid-open No. 2008-172040, the luminescent layer is exposed,and it is difficult to ensure electrical insulating properties andphysical and chemical stability of the element when a wiring is formedon the luminescent layer.

In view of the circumstances as described above, it is desirable toprovide a light-emitting element wafer that is capable of producingelements with a uniform height in large amounts and has high stabilityof element characteristics, a method of producing the light-emittingelement wafer, a light emitting element, and an electronic apparatususing the light emitting element. According to an embodiment of thepresent disclosure, there is provided a light-emitting element waferincluding a supporting substrate, a luminescent layer, a junction layer,a first inorganic film, a second inorganic film, an isolation trenchportion, and a third inorganic film. The luminescent layer is formed ofa semiconductor and has a first surface and a second surface, the firstsurface including a first electrode, the second surface including asecond electrode, the second surface being arranged between thesupporting substrate and the first surface. The junction layer joinsluminescent layer to the supporting substrate and is arranged betweenthe supporting substrate and the second surface. The first inorganicfilm is formed on the first surface. The second inorganic film is formedbetween the junction layer and the second surface. The isolation trenchportion isolates elements and is formed to have a depth such that theisolation trench portion extends from the first inorganic film to thesupporting substrate. The third inorganic film connects the firstinorganic film and the second inorganic film.

Because the light-emitting element wafer has a configuration in whichthe junction layer, the second inorganic film, the luminescent layer,and the first inorganic film are laminated on the supporting substrate,and the isolation trench portion isolates them for each element, manyelements with a uniform height can be formed on the supportingsubstrate. Therefore, it is possible to improve the uniformity of theshape of the elements on the light-emitting element wafer whilemaintaining high productivity. In addition, the first, second, and thirdinorganic films reliably protect the luminescent layer, and it ispossible to ensure electrical insulating properties of the luminescentlayer.

The first inorganic film may have a first end portion formed in parallelwith the first surface, the first end portion projecting to theisolation trench portion, and the third inorganic film may have a secondend portion that takes an example from the first end portion to projectto the isolation trench portion.

Accordingly, it is possible to increase the strength of the element.

Furthermore, the second inorganic film and the third inorganic film mayinclude a first insulating layer, a metal layer, and a second insulatinglayer, and are formed sequentially, the first insulating layer beingformed adjacent to the luminescent layer, the metal layer being formedon the first insulating layer, the second insulating layer being formedon the metal layer.

Accordingly, it is possible to cause light emitted from the luminescentlayer to be reflected on the second and third inorganic film, and toincrease the emission intensity.

Moreover, the luminescent layer may have a first concavo-convex portionformed on the first surface, and the first inorganic film may have asecond concavo-convex portion formed taking an example from the firstconcavo-convex portion.

Accordingly, it is possible to cause light emitted from the luminescentlayer to be reflected on the first and second concavo-convex portions,and to increase the emission intensity.

The luminescent layer may emit red light.

Moreover, specifically, the semiconductor may include at least any oneof materials of an AsP compound semiconductor, an AlGaInP compoundsemiconductor, and a GaAs compound semiconductor.

The first inorganic film may be the first electrode including atransparent conductive material.

Accordingly, it is possible to output, from the entire first surface,light emitted from the luminescent layer, and to increase the outputefficiency.

According to an embodiment of the present disclosure, there is provideda light emitting element including a luminescent layer, a firstinorganic film, a second inorganic film, and a third inorganic film.

The luminescent layer is formed of a semiconductor and has a firstsurface, a second surface, and a peripheral surface, the first surfaceincluding a first electrode, the second surface including a secondelectrode and being opposite to the first surface, the peripheralsurface connecting the first surface and the second surface. The firstinorganic film is formed on the first surface. The second inorganic filmis formed on the second surface. The third inorganic film is formed tocover the peripheral surface and connects the first inorganic film andthe second inorganic film.

According to an embodiment of the present disclosure, there is providedan electronic apparatus including a substrate and at least one firstsemiconductor light-emitting element. On the substrate, a drive circuitis formed. The at least one first semiconductor light-emitting elementis provided on the substrate and includes a luminescent layer, a firstinorganic film, a second inorganic film, and a third inorganic film. Theluminescent layer is formed of a semiconductor and has a first surface,a second surface, and a peripheral surface, the first surface includinga first electrode connected to the drive circuit, the second surfaceincluding a second electrode, the second surface being disposed betweenthe substrate and the first surface, the second electrode beingconnected to the drive circuit, the peripheral surface connecting thefirst surface and the second surface. The first inorganic film is formedon the first surface. The second inorganic film is formed between theluminescent layer and the second surface. The third inorganic film isformed to cover that peripheral surface and connects the first inorganicfilm and the second inorganic film.

Accordingly, the electronic apparatus can be configured to include thefirst light emitting element in which the luminescent layer is protectedand electrical insulating properties of the luminescent layer can beensured. Thus, it is possible to provide an electronic apparatus with afew flaws.

In addition, the electronic apparatus may further include a plurality ofsecond semiconductor light-emitting elements configured to emit bluelight and a plurality of third semiconductor light-emitting elementsconfigured to emit green light, in which the at least one firstsemiconductor light-emitting element may include a plurality of firstsemiconductor light-emitting element configured to emit red light, andthe plurality of first, second, and third semiconductor light-emittingelements may be arranged on the substrate.

Accordingly, it is possible to provide an electronic apparatus such as adisplay having high assembly accuracy and desired display properties byusing the plurality of first semiconductor elements with high shapeuniformity. According to an embodiment of the present disclosure, thereis provided a method of producing a light-emitting element waferincluding forming a luminescent layer having a laminated structure inwhich a semiconductor is laminated on a first substrate. A firstinorganic film is formed on a first surface of the luminescent layer,and the first substrate is removed to expose a second surface of theluminescent layer, the second surface being opposite to the firstsurface. The luminescent layer is etched from the second surface withthe first inorganic film being an etching stop layer to form a firstisolation trench that isolates the luminescent layer for each element. Asecond inorganic film that covers the second surface and a wall surfaceand a bottom surface of the first isolation trench is formed.

Because the first inorganic film laminated on the luminescent layerfunctions as an etching stop layer when the first isolation trench isformed, it is possible to increase the uniformity of the depth of thefirst isolation trench. Therefore, it is possible to improve theproductivity and to increase the shape uniformity of each element.Moreover, because the first inorganic film is formed on the bottomsurface of the first isolation trench and the second inorganic film isformed on the bottom surface, the first and second inorganic films coverthe surface of the luminescent layer. Therefore, it is possible toimprove the insulating properties of the luminescent layer and toprotect the luminescent layer.

The forming of the first isolation trench may include etching theluminescent layer by a dry etching method.

Accordingly, it is possible to reduce the side etching as compared withthe case of a wet etching method, and to perform a fine process on thefirst isolation trench.

The forming of the first isolation trench may include forming the firstisolation trench so that a cross-sectional area of the luminescent layerfor each element is gradually increased from the second surface to thefirst surface.

Accordingly, it is possible to easily form the second inorganic film.

The forming of the second inorganic film may include forming the firstinsulating layer on the second surface and the wall surface and thebottom surface of the first isolation trench, forming a metal layer onthe first insulating layer, and forming a second insulating layer on themetal layer.

Accordingly, it is possible to cause light emitted from the luminescentlayer to be reflected on the metal layer, and to increase the emissionintensity.

The method of producing a light-emitting element wafer may furtherinclude forming a first concavo-convex structure on the first surfacebefore the forming of the first inorganic film and after the forming ofthe luminescent layer.

Moreover, the forming of the first inorganic film may include taking anexample from the first concavo-convex structure to form a secondconcavo-convex structure.

Accordingly, it is possible to form the first concavo-convex structureon a flat surface to have a desired shape right after the luminescentlayer is formed. Therefore, it is possible to cause light emitted fromthe luminescent layer to be effectively reflected on the firstconcavo-convex structure, and to increase the emission intensity.

Furthermore, the method of producing a light-emitting element wafer mayfurther include detachably joining the second substrate to the firstinorganic film via a tentative a tentative junction layer before theexposure of the second surface and after the forming of the firstinorganic film.

Accordingly, it is possible to improve the handling properties of theformed element structure.

Furthermore, the method of producing a light-emitting element wafer mayfurther include forming an electrode for each device on the secondsurface before the forming of the first isolation trench after theexposure of the second surface, removing a part of the second inorganicfilm to expose the electrode after the forming of the second inorganicfilm, forming an external connection terminal that is electricallyconnected to the electrode on the second surface, and detachably joininga third substrate to the external connection terminal via the junctionlayer.

Accordingly, it is possible to easily ensure a wiring when the lightemitting element is mounted on an electronic apparatus or the like. Inaddition, because the third substrate is joined, it is possible toimprove the handling properties of the formed element structure.

Furthermore, the method of producing a light-emitting element wafer mayfurther include removing the second substrate to expose the firstinorganic film, and etching the first inorganic film remained on thebottom surface of the first isolation trench to form a second isolationtrench that isolates the first inorganic film for each element, afterthe joining of the third substrate.

Accordingly, because the elements are isolated, it is possible to easilytransfer each element to another transfer substrate, a wiring substrate,or the like.

Furthermore, the method of producing a light-emitting element wafer mayfurther include preparing a transfer substrate arranged to face thefirst inorganic film, and isolating the external connection terminalfrom the third substrate by laser ablation of the junction layer totransfer each element on the transfer substrate, after the forming ofthe second isolation trench.

By the laser ablation, it is possible to easily transfer each element toa predetermined position on the transfer substrate without processessuch as mechanical removal of a substrate. In addition, by using thetransfer substrate, the elements can be arranged at sufficientintervals, and a wiring can be smoothly formed between the elements, forexample. Therefore, it is possible to easily mount each element on thewiring substrate or the like of the electronic apparatus or the like.

As described above, according to the present disclosure, it is possibleto provide a light-emitting element wafer that is capable of producingelements with a uniform height in large amounts and has high stabilityof element characteristics, a method of producing the light-emittingelement wafer, a light emitting element, and an electronic apparatususing the light emitting element.

These and other objects, features and advantages of the presentdisclosure will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view of a light-emitting element waferaccording to a first embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view of the light-emitting elementwafer;

FIG. 3 is a schematic cross-sectional view showing the configuration ofa light emitting element shown in FIG. 1;

FIGS. 4A and 4B are each a diagram for explaining an operation oforientation of a first inorganic film shown in FIG. 1, FIG. 4A is aschematic cross-sectional view of a main portion of the light emittingelement, and FIG. 4B is a diagram showing a correlation between arefractive index N and a thickness t (nm) of the first inorganic film ofthe light emitting element and light orientation distribution;

FIGS. 5A and 5B are each a graph showing exemplary distribution ofemission intensity with respect to an emission angle θ;

FIG. 6 is a flowchart of a method of producing the light-emittingelement wafer;

FIGS. 7A, 7B and 7C are each a cross-sectional view for explaining themethod of producing the light-emitting element wafer;

FIGS. 8A and 8B are each a cross-sectional view for explaining themethod of producing the light-emitting element wafer;

FIGS. 9A and 9B are each a cross-sectional view for explaining themethod of producing the light-emitting element wafer;

FIGS. 10A and 10B are each a cross-sectional view for explaining themethod of producing the light-emitting element wafer;

FIGS. 11A and 11B are each a cross-sectional view for explaining themethod of producing the light-emitting element wafer;

FIGS. 12A and 12B are each a cross-sectional view for explaining themethod of producing the light-emitting element wafer;

FIGS. 13A and 13B are each a schematic cross-sectional view forexplaining a process of forming a reflection film (second inorganicfilm) in the method of producing the light-emitting element wafer;

FIGS. 14A and 14B are each a schematic cross-sectional view forexplaining the process of forming the reflection film (second inorganicfilm) in the method of producing the light-emitting element wafer;

FIG. 15 is a schematic plan view of a display apparatus (electronicapparatus) using the light emitting element;

FIG. 16 is a flowchart of a method of producing the display apparatus;

FIG. 17 is a schematic plan view for explaining the method of producingthe display apparatus;

FIGS. 18A, 18B and 18C are each a schematic plan view for explaining themethod of producing the display apparatus;

FIG. 19 is a schematic cross-sectional view of a light-emitting elementwafer according to a second embodiment of the present disclosure;

FIGS. 20A, 20B and 20C are each a schematic cross-sectional view forexplaining the method of producing the light-emitting element wafer;

FIGS. 21A, 21B and 21C are each a schematic cross-sectional view forexplaining the method of producing the light-emitting element wafer;

FIGS. 22A and 22B are each a schematic cross-sectional view forexplaining the method of producing the light-emitting element wafer; and

FIGS. 23A and 23B are each a schematic cross-sectional view forexplaining the method of producing the light-emitting element wafer.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be describedwith reference to the drawings.

First Embodiment

FIG. 1 is a schematic plan view of a light-emitting element wafer 100according to a first embodiment of the present disclosure, and FIG. 2 isa schematic cross-sectional view of the light-emitting element wafer100. Hereinafter, the configuration of the light-emitting element wafer100 according to this embodiment will be described. It should be notedthat in FIGS. 1 and 2, an X-axis and Y-axis represent directionsorthogonal to each other (in-plane direction of the light-emittingelement wafer 100), and a Z-axis is a direction orthogonal to the X-axisand the Y-axis (thickness direction of the light-emitting element wafer100, i.e., vertical direction).

(Semiconductor Light-Emitting Element Wafer)

The light-emitting element wafer 100 includes a supporting substrate 10,a plurality of light emitting elements 1, and isolation trench portions60. The light-emitting element wafer 100 has a configuration in whichthe plurality of light emitting elements 1 are arranged on thesupporting substrate 10. The light-emitting element wafer 100 accordingto this embodiment is used to supply the light emitting elements 1 to bemounted on an electronic apparatus such as a display apparatus and alighting apparatus, as will be described later.

The supporting substrate 10 has a surface 11 on which the light emittingelements 1 are arranged, and includes, for example, a 2 to 12-inchwafer. The supporting substrate 10 includes, for example, a materialhaving a high transmittance of a wavelength of a laser to be applied ina production process to be described later, e.g., sapphire (Al₂O₃).

The plurality of light emitting elements 1 are arranged on thesupporting substrate 10 along the X-axis direction and the Y-axisdirection, and adjacent light emitting elements 1 are isolated by theisolation trench portion 60. Specifically, the isolation trench portion60 is formed to have a depth extending from a first inorganic film 40 ofthe plurality of light emitting elements 1, which will be describedlater, to the surface 11 of the supporting substrate 10, and isolatesthe light emitting elements 1. It should be noted that in the followingdescription, the light emitting elements 1 will be referred to simplyalso as “the elements 1.”

(Light Emitting Element)

The light emitting element 1 includes a light emitting diode (LED)having a laminated structure of a semiconductor compound. In thisembodiment, the plurality of light emitting elements 1 are arranged onthe supporting substrate 10. The size of the light emitting element 1can be appropriately set depending on the size of the supportingsubstrate 10, the configuration of the electronic apparatus on which thelight emitting element 1 is mounted, or the like, and the light emittingelement 1 may have a length of not less than 1 μm and not more than 300μm along the X-axis direction, and a length of not less than 1 μm andnot more than 300 μm along the Y-axis direction, and a height of notless than 1 μm and not more than 20 μm along the Z-axis direction, forexample.

FIG. 3 is a schematic cross-sectional view showing the configuration ofthe light emitting element 1. The light emitting element 1 includes aluminescent layer 20, a junction layer 30, the first inorganic film 40,a second inorganic film 520, and a third inorganic film 530. Moreover,the second inorganic film 520 and the third inorganic film 530 arecollectively referred to also as the reflection film (second inorganicfilm 50).

The luminescent layer 20 has a first surface 201 including a firstelectrode 710 and a second surface 202 that includes a second electrode(electrode) 720 and is arranged between the supporting substrate 10 andthe first surface 201, and is formed of a semiconductor.

The junction layer 30 is arranged between the supporting substrate 10and the second surface 202, and joins the luminescent layer 20 to thesupporting substrate 10.

The first inorganic film 40 is formed on the first surface 201.

The second inorganic film 520 is formed between the junction layer 30and the second surface 202.

The third inorganic film 530 connects the first inorganic film 40 andthe second inorganic film 520.

Hereinafter, each component of the light emitting element 1 will bedescribed.

(Luminescent Layer)

In this embodiment, the luminescent layer 20 has a laminated structureof a semiconductor that emits red light, and includes, for example, aGaAs semiconductor compound and an AlGaInP semiconductor compound. Theluminescent layer 20 includes a first conductive-type firstsemiconductor layer 21, an active layer 23 formed on the firstsemiconductor layer 21, and a second conductive-type secondsemiconductor layer 22 formed on the active layer 23. In thisembodiment, the first conductive type and the second conductive typerepresent an n-type and a p-type, respectively, but are not limitedthereto.

The luminescent layer 20 has the first surface 201, the second surface202 opposite to the first surface 201, and a peripheral surface 203 thatconnects the first surface 201 and the second surface 202. The firstsurface 201 and the second surface 202 are arranged to face each otherin the Z-axis direction. The entire thickness of the luminescent layer20 is not less than about 1 μm and not more than 20 μm. The entire shapeof the luminescent layer 20 is not particularly limited. For example,the luminescent layer 20 is formed to have a truncated square pyramidshape. In this case, the luminescent layer 20 is formed so that thecross-sectional area of the luminescent layer 20 perpendicular to theZ-axis direction is gradually increased from the second surface 202 tothe first surface 201 and the peripheral surface 203 has four taperedsurfaces.

The first surface 201 has a connection area 2011 in which the firstelectrode 710 is formed, and a light extraction area 2012 in which afirst concavo-convex portion 210 is formed. The connection area 2011occupies the center portion of the first surface 201, and the lightextraction area 2012 is arranged to surround the connection area 2011.It should be noted that the position and shape of the connection area2011 are not limited, and a plurality of connection areas 2011 may bearranged in an island shape.

The first concavo-convex portion 210 may be appropriately configured toobtain desired optical properties of output light. For example, thefirst concavo-convex portion 210 may have a prism shape having a ridgeline as shown in FIG. 3, or groove-like concave portions may be formedon a flat surface (convex portion) (see FIGS. 7 to 12).

Moreover, “the first surface 201 is substantially perpendicular to theZ-axis direction” represents that a reference surface 201 s of the firstsurface 201 is substantially perpendicular to the Z-axis direction. Inaddition, the reference surface 201 s of the first surface 201represents a virtual flat surface including top portions (top surface)of a plurality of convex portions of the first concavo-convex portion210.

In this embodiment, the second surface 202 is formed to have the areasmaller than that of the first surface 201 when view from the Z-axisdirection. The second surface 202 has a connection area 2021 thatoccupies the center portion of the second surface 202, on which thesecond electrode 720 is formed, and a reflection area 2022 thatsurrounds the connection area 2021. The reflection area 2022 is coveredby the second inorganic film 520 of the reflection film 50.

In the luminescent layer 20, light emitted from the active layer 23 isoutput via the light extraction area 2012 of the first surface 201. Inthis embodiment, the peripheral surface 203 is formed as a taperedsurface and is covered by the third inorganic film 530 to be describedlater, and the light extraction area 2012 of the first surface 201 hasthe first concavo-convex portion 210. Accordingly, it is possible toincrease the output efficiency by reflecting the light toward the upperside of the Z-axis direction, and to control the orientation of light.

The first semiconductor layer 21 has a laminated structure of a firstcontact layer 211 and a first cladding layer 212. The first contactlayer 211 is connected to the second electrode 720, and is formed tohave almost the same area as that of the second electrode 720 whenviewed from the Z-axis direction, for example. The first contact layer211 includes a material that is capable of forming ohmic contact withthe second electrode 720, e.g., n-type GaAs. The first cladding layer212 is formed on the first contact layer 211 to occupy the entire secondsurface 202 when viewed from the Z-axis direction. Specifically, anexposed surface of the first cladding layer 212 forms the reflectionarea 2022 of the second surface 202. The first cladding layer 212includes, for example n-type AlGaInP.

The active layer 23 has a multiquantum well structure of a well layerand a barrier layer formed of semiconductors having differentcompositions, for example, and is formed to be capable of emitting lightof a predetermined wavelength. The active layer 23 according to thisembodiment is capable of emitting red light of a light emissionwavelength of about 500 to 700 nm. The active layer 23 includes about 10to 20 well layers and about 10 to 20 barrier layers, for example. Eachwell layer includes GaInP and each barrier layer includes AlGaInP. Thewell layers and the barrier layers are laminated to each other.

The second semiconductor layer 22 has a laminated structure of a secondcladding layer 221 and a second contact layer 222. The second claddinglayer 221 is formed on the active layer 23, and includes, for example,p-type AlGaInP. The second contact layer 222 is formed on the secondcladding layer 221, and is connected to the first electrode 710. Thesecond contact layer 222 occupies the entire first surface 201 whenviewed from the Z-axis direction, and the exposed surface of the secondcontact layer 222, on which the first electrode 710 is not formed, formsthe light extraction area 2012 of the first surface 201. The secondcontact layer 222 includes a material that is capable of forming ohmiccontact with the first electrode 710, e.g., p-type GaP. It should benoted that in the first and second semiconductor layers 21 and 22,another layer may be appropriately provided between the above-mentionedlayers. For example, the second semiconductor layer 22 may include aprotective layer between the active layer 23 and the second claddinglayer 221. The protective layer includes undoped AlGaInP, and is capableof preventing dopants of the second cladding layer 221 or the like fromdiffusing to the side of the active layer 23. Moreover, the materialshown in each layer of the luminescent layer 20 is given for exemplarypurposes, and can be appropriately selected in view of the configurationof the light emitting element 1, desired light emission properties, andthe like.

The first electrode 710 is formed in the connection area 2011 of thefirst surface 201, and is connected to the second contact layer 222.Specifically, the surface of the first electrode 710 forms theconnection area 2011 of the first surface 201. The shape of the firstelectrode 710 is not particularly limited, and the first electrode 710is formed to have an elliptical shape, a circular shape, or a rectangleshape, with a short axis length of about 1 to 10 μm along the X-axisdirection and a long axis length of about 1 to 10 μm along the Y-axisdirection, for example. In addition, the thickness of the firstelectrode 710 may be 200 to 600 μm, for example. The first electrode 710may include a metal material such as Ti, Pt, Au, Ge, Ni, and Pd, analloy or laminated body containing them, or a transparent conductivematerial such as ITO.

The second electrode 720 is formed in the connection area 2021 of thesecond surface 202, and is connected to the first contact layer 211.Specifically, the surface of the second electrode 720 forms theconnection area 2021 of the second surface 202. The shape of the secondelectrode 720 is not particularly limited, and the second electrode 720is formed to have a circular shape, for example. However, the shape ofthe second electrode 720 may be an elliptical shape or a rectangularshape. In addition, the thickness of the second electrode 720 may be 200to 600 μm, for example. The second electrode 720 may include a metalmaterial such as Ti, Pt, Au, Ge, Ni, and Pd, an alloy or laminated bodycontaining them, or a transparent conductive material such as ITO.

(First Inorganic Film)

The first inorganic film 40 is formed to cover the light extraction area2012 of the first surface 201.

Specifically, the first inorganic film 40 includes a connection hole 420that is formed on the first electrode 710 (the connection area 2011) andfaces the first electrode 710. The thickness of the first inorganic film40 is, for example, not less than 200 μm and not more than 600 μm, morefavorably, not less than 300 μm and not more than 500 μm.

Moreover, the first inorganic film 40 has a second concavo-convexportion 410 that is formed taking an example from the firstconcavo-convex portion 210 of the first surface 201, and a first endportion 41 that is formed around the second concavo-convex portion 410.The first end portion 41 forms a flat surface that is formed in parallelwith the first surface 201, and projects outward of the first surface201. Here, “formed in parallel with the first surface 201” representsbeing formed in parallel with the reference surface 201 s of the firstsurface 201.

The first inorganic film 40 has permeability, and includes siliconnitride (hereinafter, referred to as SiN) having a refractive index ofnot less than 1.9 and not more than 2.3, silicon oxide such as SiO₂, ora laminated body of SiN and SiO₂, for example.

Alternatively, the first inorganic film 40 may include an insulatingmaterial such as TiN and TiO₂. Accordingly, it is possible to ensureinsulating properties of the first surface 201 of the luminescent layer20, and to cause the first inorganic film 40 to function as a protectionfilm of the first surface 201. Furthermore, as will be described later,because the first inorganic film 40 has a predetermined thickness and apredetermined refractive index, it is possible to increase the emissionintensity of the light emitting element 1 in the front direction.

(Reflection Film)

The reflection film 50 includes the second inorganic film 520 and thethird inorganic film 530, and is formed to cover the second surface 202and the peripheral surface 203 of the luminescent layer 20. Thereflection film 50 reflects, to the side of the first surface 201, lightemitted from the luminescent layer 20, which contributes to improve theoutput efficiency.

The second inorganic film 520 is formed to cover the reflection area2022 of the second surface 202 of the luminescent layer 20. In addition,the second inorganic film 520 includes a connection hole 540 that isformed on the second electrode 720 (connection area 2021) and faces thesecond electrode 720. The entire thickness of the second inorganic film520 is, for example, not less than 0.1 μm.

The third inorganic film 530 is formed continuously with the secondinorganic film 520, and is formed to cover the entire peripheral surface203 of the luminescent layer 20. Moreover, the third inorganic film 530has a second end portion 510 that projects outward taking an examplefrom the first end portion 41 of the first inorganic film 40.Specifically, the second end portion 510 is formed as a flange portionof the reflection film 50 that is folded in parallel with the firstsurface 201. The thickness of the area along the peripheral surface 203of the third inorganic film 530 is, for example, not less than 0.2 μm,and the thickness of the second end portion 510 is, for example, notless than 0.2 μm and not more than 5 μm.

With this configuration, a height H2 of the second end portion 510 ofthe reflection film 50 (third inorganic film 530) along the Z-axisdirection from the surface 11 of the supporting substrate 10 is lowerthan a height H1 of the surface of the first inorganic film 40 at thefirst end portion 41 (see FIG. 2).

The reflection film 50 includes a first insulating layer 51 formedadjacent to the luminescent layer 20, a metal layer 53 formed on thefirst insulating layer 51, and a second insulating layer 52 formed onthe metal layer 53. Specifically, the reflection film 50 has a laminatestructure in which the reflection film 50 is continuously formed withthe second and third inorganic films 520 and 530.

The first insulating layer 51 covers from the reflection area 2022 ofthe second surface 202 to the peripheral surface 203, and is formed overthe second end portion 510 located immediately below the first endportion 41. On the other hand, the second insulating layer 52 is formedin an area overlapped with the first insulating layer 51 when viewedfrom the Z-axis direction. The first and second insulating layers 51 and52 may include silicon oxide such as SiO₂, SiN, TiN, TiO₂, anotherinsulating inorganic material, or a laminated body thereof.

The metal layer 53 includes an opening 531 that is larger than theconnection hole 540, and is formed from a part of the reflection area2022 to the second end portion 510 via the peripheral surface 203, forexample.

The metal layer 53 has a function to reflect, to the first surface 201,light emitted from the luminescent layer 20. Specifically, a materialhaving high reflection efficiency of the light emitted from theluminescent layer 20 only has to be adopted. In this embodiment, themetal layer 53 includes a metal material such as Al, Au, Ti, Cu, Ni, andAg, or an alloy or laminated body thereof.

Moreover, because the metal layer 53 is formed to the second end portion510, it is possible to reflect light that has entered the first endportion 41 upward in the Z-axis direction, and to output the reflectedlight. Accordingly, it is possible to increase the intensity of outputlight in the front direction.

The connection hole 540 is formed by the first and second insulatinglayers 51 and 52. Specifically, to the peripheral surface of theconnection hole 540, the first and second insulating layers 51 and 52are exposed, and the metal layer 53 is not exposed. Accordingly,insulating properties between the metal layer 53 and the secondelectrode 720 are maintained.

The first and second end portions 41 and 510 each have an end surface inparallel with the Z-axis direction. In this embodiment, these endsurfaces are formed in the same plane. Moreover, as shown in FIG. 3, thefirst and second insulating layers 51 and 52 and the metal layer 53 maybe exposed from the end surface of the second end portion 510.Accordingly, it is possible to increase the heat radiation property ofthe light emitting element 1. Alternatively, the metal layer 53 may beformed not to be exposed from the end surface of the second end portion510, or may be formed to cover only the peripheral surface 203.

Furthermore, the light emitting element 1 according to this embodimentfurther includes an external connection terminal 730 connected to thesecond electrode 720 that is exposed from the connection hole 540.

(External Connection Terminal)

The external connection terminal 730 is arranged between the junctionlayer 30 and the second inorganic film 520. The external connectionterminal 730 is formed to be connected to the second electrode 720 andto cover the second inorganic film 520 and the second electrode 720, andhas a rectangular shape with almost the same size as the secondinorganic film 520 when viewed from the Z-axis direction. The thicknessof the external connection terminal 730 is not particularly limited, butis not less than 0.1 μm and not more than 0.5 μm, for example. Theexternal connection terminal 730 includes a metal material such as Al,Au, and Ti, or an alloy or laminated body containing them.

It should be noted that as shown in FIG. 3, a resin film 732 may beformed so that a concave portion 733 of the external connection terminal730, which is formed due to the connection hole 540, is embedded. Theresin film 732 includes adhesive resin material, for example. It shouldbe noted that the resin film 732 may be formed not only in the concaveportion 733 but also in the entire area in which the external connectionterminal 730 is formed (see resin R3 in FIG. 12A).

(Junction Layer)

With reference to FIG. 2, the junction layer 30 is arranged between theexternal connection terminal 730 and the supporting substrate 10, andjoins the light emitting element 1 to the supporting substrate 10. Thethickness of the junction layer 30 is, for example, not less than 0.2 μmand not more than 2 μm. The junction layer 30 includes a thermoplasticresin material having adhesiveness such as polyimide. Therefore, thejunction layer 30 is ablated when being heated to evaporation byirradiation of a laser light having a predetermined wavelength, forexample. Accordingly, the junction layer 30 can be easily isolated fromthe supporting substrate 10 by the power of the ablation. The materialof the junction layer 30 is not limited to the above, and ultravioletcurable resin, an adhesive sheet, an adhesive material can be adopted,for example.

In each light emitting element 1 having such a configuration, thejunction layer 30, the external connection terminal 730, the secondinorganic film 520, the luminescent layer 20, and the first inorganicfilm 40 are laminated in the stated order on the supporting substrate10. Moreover, these layers are isolated for each element 1 by theisolation trench portions 60 as described above. Specifically, in thelight-emitting element wafer 100, the light emitting elements 1 can beformed to have a uniform height on the entire supporting substrate 10.Specifically, variation in heights of the plurality of light emittingelements 1 from the surface 11 on the light-emitting element wafer 100can be suppressed to 10% or less, for example.

Furthermore, the first, second, and third inorganic films 40, 520, and530 cover the entire surface of the luminescent layer 20 excluding theconnection areas 2011 and 2021. Accordingly, it is possible to ensureinsulating properties of the luminescent layer 20 and physical andchemical stability of the luminescent layer 20.

Moreover, in the metal layer 53 having a tapered surface, and the firstand second concavo-convex portions 210 and 410, and it is possible toreflect light emitted from the luminescent layer 20 and to efficientlyoutput the light from the first surface 201.

Furthermore, by adjusting the thickness and the refractive index of thefirst inorganic film 40, it is possible to use interference of lighthaving a predetermined wavelength, and to adjust the orientation ofoutput light of the light emitting element 1. Hereinafter, the operationof the orientation of the output light of the first inorganic film 40will be described.

(Operation of Orientation of First Inorganic Film)

FIG. 4A is a schematic cross-sectional view of the luminescent layer 20of light emitting element 1, and FIG. 4B is a diagram showing thecorrelation between the refractive index N and the thickness t (nm) ofthe first inorganic film 40 and the light orientation distribution. Morespecifically, the horizontal axis represents a value of Nt/A when thewavelength of output light is assumed to be A (nm), and the verticalaxis represents the ratio of actual emission intensity and emissionintensity when the far field pattern (FFP) has a Lambertian profile in adirection at an angle of 45 degrees to the normal line direction of thefirst surface 201 (direction in parallel with the Z-axis direction)(hereinafter, the ratio being referred to as Lambertian curve ratio). Itshould be noted that the Lambertian represents the state of the FFP ofoutput light. Assuming that an emission angle from the normal linedirection of the output surface is θ, the Lambertian represents thelight distribution such that the value of the FFP of output light isconstant regardless of the angle, when the FFP of output light on anoutput surface is divided by cos θ. For example, when the FFP of outputlight has a Lambertian profile, the emission intensity has a maximumvalue in the front direction (θ=0°), and the output intensity tends tobe decreased as the absolute value of the emission angle θ is increased.

As shown in FIG. 4B, values of the distribution of the Lambertian carveratio change at a cycle of Nt/λ being about ½ due to the influence ofthe interference of light. Specifically, the value is concave down(maximum) when Nt/λ is about 1.5 (6/4) (hereinafter, referred to as(B)), and is concave up (minimum) when Nt/λ is about 1.25 (5/4)(hereinafter, referred to as (A)) and about 1.79 (7/4+0.05)(hereinafter, referred to as (C)).

Here, Figs. are each a graph showing the distribution of emissionintensity with respect to the emission angle θ, FIG. 5A shows an exampleof the (B) in the graph of FIG. 4B in which the emission intensity ismaximum, and FIG. 5B shows an example of the (A) and (C) in the graph ofFIG. 4B in which the emission intensity is minimum. In FIGS. 5A and 5B,the FFP in the case of the Lambertian is represented by a light coloredline as a reference.

As shown in FIG. 5A, in the case of the (B), the emission intensity islarge in the range of −70<θ<70 as compared with the case of Lambertian,and the emission intensity in the front direction (θ=0) is relativelysmall. On the other hand, as shown in FIG. 5B, in the case of the (A)and (C), the emission intensity is small as a whole as compared with thecase of Lambertian, and the emission intensity in the front direction isrelatively large.

Based on these results, in order to increase the emission intensity inthe front direction, it only needs to adjust the value of Nt/λ in thefirst inorganic film 40 to be concave up as in the (A) and (C) in thegraph of FIG. 4B, for example. Therefore, based on the value of Nt/λ andthe fluctuation cycle of Nt/λ in the (A) and (C), it only needs toadjust N (refractive index of the first inorganic film 40), t (thicknessof the first inorganic film 40), and λ (wavelength of output light ofthe luminescent layer 20) so as to satisfy the following equation (1):Nt/λ=(x+1)/4±0.15 (x=2,4,6,8)  (1).

In this embodiment, λ is about 630 (nm), for example. Moreover, in thecase where SiN is used for the first inorganic film 40, the refractiveindex N satisfies the equation, 2.0≤N≤2.1, for example. Therefore, bysetting the thickness t of the first inorganic film 40 to 141.75 (nm),393.75 (nm), 552.25 (nm), and 708.75 (nm) in the case where N=2.0 andx=2, 4, 6, and 8, respectively, it is possible to increase the emissionintensity in the front direction.

As described above, by adjusting the material and the thickness of thefirst inorganic film 40 depending on the wavelength of light emittedfrom the luminescent layer 20 based on the equation (1), it is possibleto increase the emission intensity of the light emitted from theluminescent layer 20 in the front direction due to the constructiveinterference of light having a predetermined wavelength. For example, byadopting SiN that satisfies the equation, 1.9≤N≤2.3, more favorably,2.0≤N≤2.1, or a laminated structure of SiN and SiO₂, or adjusting thethickness of the first inorganic film 40 to satisfy the equation,200≤N≤600, more favorably, 300≤N≤500, so as to satisfy the equation (1),it is possible to maintain the productivity of the first inorganic film40 and to improve the light orientation of the light emitting element 1.

Hereinafter, a method of producing the light-emitting element wafer 100according to this embodiment will be described.

(Method of Producing Light-Emitting Element Wafer)

FIG. 6 is a flowchart of a method of manufacturing the light-emittingelement wafer 100 according to this embodiment, and FIGS. 7 to 12 areeach a schematic cross-sectional view for explain the production method.Hereinafter, a description will be given with reference to thesefigures.

A luminescent layer 20 a is formed on a first substrate 10 a first(ST101). Here, on the first substrate 10 a, a metal organic chemicalvapor deposition (MOCVD) method is used to cause crystal growth oflayers of the luminescent layer 20 a. The first substrate 10 a is awafer including, for example, gallium arsenide (GaAs), and a crystalsurface on which the luminescent layer 20 a is formed is, for example, aC surface (0001).

As described above, on the first substrate 10 a, a plurality of elementareas 1 a corresponding to the elements 1 are defined along the X-axisdirection and the Y-axis direction. The plurality of element areas 1 aare typically defined by a virtual boarder line L.

On the first substrate 10 a, crystal growth of a stop layer 214 a, afirst contact layer 211 a, and a first cladding layer 212 a is caused inthe stated order first. The first stop layer 214 a, the first contactlayer 211 a, and the first cladding layer 212 a are first-conductivetype. The stop layer 214 a functions as an etching stop layer when thefirst substrate 10 a is removed, and only needs to be formed of amaterial that is capable of ensuring etch selectivity ratio that islarger than a predetermined value with the first substrate 10 a. Of thelayers, the stop layer 214 a is removed together with the firstsubstrate 10 a in a subsequent process. Therefore, the firstsemiconductor layer 21 of the light emitting element 1 includes thefirst contact layer 211 a and the first cladding layer 212 a.

Next, a multiquantum well layer 23 a is formed. In the multiquantum welllayer 23 a, 10 to 20 well layers and 9 to 20 barrier layers arelaminated to each other, for example. The multiquantum well layer 23 aforms the active layer 23 of the light emitting element 1.

Furthermore, on the multiquantum well layer 23 a, crystal growth of asecond cladding layer 221 a and a second contact layer that are secondconductive-type is sequentially caused. It should be noted that thesecond contact layer is not shown in FIGS. 7 to 12. The secondsemiconductor layer 22 of the light emitting element 1 includes thesecond cladding layer 221 a and the second contact layer.

It should be noted that the luminescent layer 20 a is not limited theabove-mentioned configuration, and can be appropriately modified asnecessary.

Next, as shown in FIG. 7A, on a first surface 201 a, a firstconcavo-convex structure 210 a is formed (ST102). The firstconcavo-convex structure 210 a is formed by a photolithographytechnique, a reactive ion etching (RIE) method, or the like. Moreover,in this process, a connection area 2011 a at the center of the elementarea 1 a and a boundary area 610 a between the element areas 1 a may becovered by a mask (not shown) not to form the first concavo-convexstructure 210 a. Accordingly, the connection area 2011 a and theboundary area 610 a can each have a flat surface. The first electrode710 a is formed in the connection area 2011 a in the next process, andthe first end portion 41 and the isolation trench portion 60 are formedin the boundary area 610 a subsequently.

Next, as shown in FIG. 7B, the first electrode 710 a is formed in theconnection area 2011 a of the first surface 201 a (ST103). The firstelectrode 710 a is formed by an appropriate method such as a sputteringmethod, a deposition method, an ion plating method, and a platingmethod, and is pattern-formed in a predetermined shape such as anelliptical shape. In addition, at least one first electrode 710 a isformed for each element area 1 a. Then, as shown in FIG. 7C, a firstinorganic film 40 a is formed on the first surface 201 a including thefirst electrode 710 a (ST104). The first inorganic film 40 a includesSiN, TiO₂, SiO₂, SiON, NiO, AlO, or a lamination film thereof. Inaddition, the first inorganic film 40 a is formed to have a uniformthickness taking an example from the first surface 201 a.

Specifically, in this process, a second concavo-convex structure 410 ais formed taking an example from the first concavo-convex structure 210a.

Next, a second substrate 10 b is detachably joined on the firstinorganic film 40 a via a temporal junction layer 31 a (ST105). In thisembodiment, the temporal junction layer 31 a has a laminated structureof a first resin film 311 a, an adhesive layer 312 a, and second resinfilm 313 a. It should be noted that FIG. 8A shows the state verticallyinverted from the state shown in FIG. 7C so that the first substrate 10a is arranged on the upper side of the figure.

As shown in FIG. 8A, the first resin film 311 a is formed on the firstinorganic film 40 a by application or the like first. Next, the adhesivelayer 312 a is attached on the first resin film 311 a. The adhesivelayer 312 a includes a resin adhesive sheet or an adhesive material.Furthermore, the second resin film 313 a is formed on the adhesive layer312 a by application or the like.

The first and second resin film 311 a and 313 a may include athermosetting resin material having adhesiveness such as polyimide, forexample. Accordingly, in the process of removing the second substrate 10b to be described later, the first and second resin film 311 a and 313 aare ablated when being heated to evaporation by irradiation of a laserlight having a predetermined wavelength, for example. Accordingly, theadhesiveness of first and second resin film 311 a and 313 a can beeasily lost by the power of the ablation. The thermosetting resinmaterial is not limited to the above, and any material that is capableof absorbing a laser light having a predetermined wavelength and causingablation can be used.

Then, as shown in FIG. 8A, the second substrate 10 b is attached on thesecond resin film 313 a of the temporal junction layer 31 a. In thisembodiment, the second substrate 10 b is a disk-shaped semiconductorwafer including sapphire (Al₂O₃) or the like.

It should be noted that the configuration of the temporal junction layer31 a is not limited to the above, and the temporal junction layer 31 amay include only the first resin film 311 a and the adhesive layer 312a, for example. Moreover, in the above-mentioned process, a part or allof the temporal junction layer 31 a may be formed on the secondsubstrate 10 b in advance, and the first inorganic film 40 a and thesecond substrate 10 b may be joined.

Next, as shown in FIG. 8B, the first substrate 10 a is removed to exposea second surface 202 a of the luminescent layer 20 a, which is oppositeto the first surface 201 a (ST106). In this process, the first substrate10 a is removed by a wet etching method or the like first. At this time,an etchant having a high etch selectivity ratio with the stop layer 214a and the first substrate 10 a is used. Accordingly, the wet etching issuppressed at the stop layer 214 a, and thus the first substrate 10 acan be reliably removed. Furthermore, the stop layer 214 a is removed bya dry etching method or the like. Accordingly, the first contact layer211 a is exposed on the luminescent layer 20 a.

It should be noted that in this process, the second surface 202 a isformed of the surface of the first contact layer 211 a. Moreover, theconfiguration including the layers from the first contact layer 211 a tothe second cladding layer 221 a (second contact layer) is referred to asa luminescent layer 20 b.

Next, with reference to FIG. 9A, a second electrode (electrode) 720 a isformed on the second surface 202 a (ST107). The second electrode 720 ais pattern-formed in a circular shape having a diameter of about 1 to 20μm, for example. At least one second electrode 720 a is formed for eachelement area 1 a.

Furthermore, in this embodiment, the first contact layer 211 a is etchedusing the second electrode 720 a as a mask. Accordingly, as shown inFIG. 9A, the first contact layer 211 a is removed excluding the arealocated immediately below the second electrode 720 a. The pattern-formedfirst contact layer is referred to as the first contact layer 211 b.Moreover, in this process and following processes, the second surface isformed of the surfaces of the second electrode 720 a and a secondcladding layer 212 a, and is referred to as the second surface 202 b.

Next, as shown in FIG. 9B, the luminescent layer 20 a is etched from thesecond surface 202 b using the first inorganic film 40 a as an etchingstop layer, and a first isolation trench 61 a that isolates theluminescent layer 20 a for each element (element area) la is formed(ST108). In this process, the luminescent layer 20 a is etched by a dryetching method, for example.

A mask layer M1 is formed for each element area 1 a on the secondsurface 202 b first. The mask layer M1 is pattern-formed for eachelement area 1 a in a shape corresponding to the second surface 202after the formation of the element 1. Specifically, the mask layer M1includes an opening M11 formed along the boundary between the elementareas 1 a. Moreover, the material of the mask layer M1 may be anymaterial that has a low etching rate in the etchant used in thisprocess. For example, SiO₂, SiN, Ti, Ni, Cr, Al or the like is employed.

Then, a dry etching is performed via the opening M11 of the mask layerM1 to form the first isolation trench 61 a along the boundary betweenthe element areas 1 a. At this time, an etching gas (etchant) having ahigh etch selectivity ratio with a semiconductor including AlGaInP,GaAs, GaP, or the like being the material of the luminescent layer 20 aand SiN or SiO₂ being the material of the first inorganic film 40 a isused. Examples of such an etchant include SiCl₄. Accordingly, even ifthe etching rate is not uniform in the plane of the first substrate 10a, the first isolation trench 61 a can be formed in the plane to have auniform depth because the first inorganic film 40 a functions as anetching stop layer. It should be noted that in the followingdescription, the etching gas used in a dry etching is also referred toas the etchant.

Moreover, in this process (ST108), the luminescent layer 20 a can beformed for each element 1 a to have a cross-sectional area thatgradually is increased from the second surface 202 b to the firstsurface 201 a. Specifically, the cross-sectional area of the opening ofthe first isolation trench 61 a on the side of the second surface 202 bis larger than the cross-sectional area of a bottom surface 612 a. Sucha first isolation trench 61 a can be appropriately formed under thecondition of taper etching. The specific etching condition depends onthe size of a wafer, the configuration of an etching apparatus, and thelike. For example, the antenna power is 100 to 1000 W, the bias power is10 to 100 W, the processing pressure is 0.25 to 1 Pa, and the substratetemperature is 100 to 200° C. It should be noted that the“cross-sectional area” represents a cross-sectional area in a directionperpendicular to the Z-axis direction. Then, after the first isolationtrench 61 a is formed, the mask layer M1 is removed by an etching or thelike.

In this process (ST108), the first isolation trench 61 a having a wallsurface 611 a to be a tapered surface and the bottom surface 612 a isformed. The end surfaces of the layers of the luminescent layer 20 bexcluding the first contact layer 211 b are exposed to the wall surface611 a, and the first inorganic film 40 a is exposed to the bottomsurface 612 a. Moreover, the wall surface 611 a corresponds to theperipheral surface 203 of the light emitting element 1.

Next, as shown in FIG. 10A, a reflection film (second inorganic film) 50a that covers the wall surface 611 a and the bottom surface 612 a of thefirst isolation trench 61 a and the second surface 202 b is formed(ST109).

As described above, the reflection film 50 a has a laminated structureof a first insulating layer 51 a, a metal layer 53 a, and a secondinsulating layer 52 a, which are formed in the stated order.

FIGS. 13 and 14 are each a schematic cross-sectional view for explainingthis process (ST109). It should be noted that in FIGS. 13 and 14, thelayers of the first and second concavo-convex structures 210 a and 410 aand the temporal junction layer 31 a, and the second substrate 10 b arenot shown.

As shown in FIG. 13A, the first insulating layer 51 a is formed on thewall surface 611 a and the bottom surface 612 a of the first isolationtrench 61 a and the second surface 202 b (ST109-1). In this process, aCVD method, a sputtering method, or the like can be used.

Alternatively, a resin material such as SOG (applying material forforming an SiO₂ coating film) can be used to form the first insulatinglayer 51 a by a spin coating method or application. Moreover, thesemethods can be used to form a laminated structure. Specifically, in thisembodiment, because the wall surface 611 a is formed to have a taperedshape, the first insulating layer 51 a can be easily formed using amaterial having a relatively low viscosity.

Next, the metal layer 53 a is formed on the first insulating layer 51 a(ST109-2). For the pattern-formation of the metal layer 53 a in thisprocess, a lift-off method is adopted, for example. Specifically, asshown in FIG. 13B, a resist R1 is formed on the area in which the metallayer 53 a should be prevent from being formed. As the resist R1, apositive resist or a negative resist may be adopted. It should be notedthat by using the positive resist, the halation during exposure can besuppressed. Moreover, the area in which the resist R is formedspecifically includes the area including the second electrode 720 a andthe area at the center of the bottom surface 612 a when viewed from theZ-axis direction. These areas correspond to the opening 531 of the metallayer 53 and the isolation trench portions 60 when the element 1 iscompleted, respectively. Specifically, a metal layer 53 b is formedfirst on the entire surface of the first insulating layer 51 a includingthe resist R1 by an appropriate method such as a sputtering method, adeposition method, an ion plating method, and a plating method. Forexample, for the metal layer 53 b, a laminate structure of Al and Au isappropriately adopted. Accordingly, it is possible to reflect lighthaving a wavelength of about 500 to 700 nm at a high reflectance.Moreover, by using a sputtering method, it is possible to improve theadhesiveness between the metal layer 53 b and the first insulating layer51 a.

Then, the resist R1 to which the metal layer 53 b is attached isremoved. Accordingly, as shown in FIG. 14A, the metal layer 53 aincluding an opening 531 a corresponding to the opening 531 and a secondopening 532 a is formed.

Furthermore, as shown in FIG. 14B, the second insulating layer 52 a isformed on the metal layer 53 a (ST109-3). In this process, the entiresurfaces of the metal layer 53 a and the first insulating layer 51 a arecovered by the second insulating layer 52 a. As the method of formingthe second insulating layer 52 a, a CVD method, a sputtering method, oran application method can be appropriately adopted similarly to thefirst insulating layer 51 a.

Accordingly, in the entire inner surfaces of the second surface 202 band the first isolation trench 61 a, the reflection film 50 a is formed.The reflection film 50 a on the second surface 202 b corresponds to thesecond inorganic film 520, and the reflection film 50 a on the wallsurface 611 a corresponds to the third inorganic film 530.

As described above, in this embodiment, the metal layer 53 a is formedby a lift-off method. Therefore, it is possible to suppress theinfluence of side etching of the resist and to form the metal layer 53 ahaving a desired shape. Moreover, even if the metal layer 53 a is formedof chemically stable metal, it is possible to easily perform a fineprocess.

As the next process, as shown in FIG. 10B, a part of the reflection film50 a is removed to expose the second electrode 720 a (ST110).Accordingly, a connection hole 540 a is formed in the first insulatinglayer 51 a and the second insulating layer 52 a of the reflection film50 a. In this process, a resist (not shown) on which the pattern of theshape corresponding to the second electrode 720 a is formed is formedfirst, and an etching method or the like via the resist is used.

Then, as shown in FIG. 11A, an external connection terminal 730 a thatis electrically connected to the second electrode 720 a is formed on thesecond surface 202 b (ST111). A metal film may be formed on the secondsurface 202 b by an appropriate method such as a sputtering method, adeposition method, an ion plating method, and a plating method, and themetal film may be patterned into a predetermined shape by a wet etchingmethod, a dry etching, or the like, thereby forming the externalconnection terminal 730 a according to this process. Alternatively, ametal film may be formed after a resist having a predetermined patternis formed by a lift-off method, thereby forming the external connectionterminal 730 a. Accordingly, the external connection terminal 730 a isformed on the second electrode 720 a in the connection hole 540 a and onthe reflection film 50 a on the second surface 202 b.

Moreover, accordingly, a space portion surrounded by the adjacentexternal connection terminals 730 a on the first isolation trench 61 ais formed. Hereinafter, a description will be made with the firstisolation trench 61 a and the space portion being collectively referredto as the trench portion 613 a.

Next, a third substrate 10 c is detachably joined on the externalconnection terminal 730 a via a junction layer 30 a (ST112).

As shown in FIG. 11B, in this process, a resin R2 is filled in thetrench portion 613 a first. Accordingly, when the third substrate 10 cis joined, it is possible to prevent a void from being generated due tothe trench portion 613 a, for example. The method of filling the resinR2 is not particularly limited, and an applying method, a spin coatingmethod, spraying, or a dipping method can be appropriately adopted, forexample.

Furthermore, the resin R2 is etched back after the application. Thus,the resin R2 can be formed to have almost the same height as the surfaceof the external connection terminal 730 a. The material of the resin R2is not particularly limited.

Next, as shown in FIG. 12A, for example, an adhesive resin R3 is formedon the resin R2 and the external connection terminal 730 a. Accordingly,it is possible to improve the adhesiveness between the junction layer 30a and the external connection terminal 730 a. Moreover, the resin R3corresponds to the resin film 732 described above. The method of formingthe resin R3 is not particularly limited, and an applying method, a spincoating method, spraying, or a dipping method can be appropriatelyadopted, for example. It should be noted that FIG. 12A shows the statevertically inverted from the state shown in FIG. 11B.

Then, on the external connection terminal 730 a and the resin R3, thethird substrate 10 c on which the junction layer 30 a is formed isjoined. The third substrate 10 c corresponds to the supporting substrate10, and is a disk-shaped semiconductor wafer including sapphire or thelike.

An applying method, a spin coating method, spraying, a dipping method orthe like is appropriately adopted to form the junction layer 30 a on thethird substrate 10 c. The junction layer 30 a may include athermosetting resin material having adhesiveness such as polyimide. Inthis case, any material that is capable of absorbing a laser lighthaving a predetermined wavelength and causing ablation can be usedsimilarly to the second resin film 313 a.

It should be noted that the method of joining the third substrate 10 cis not limited to the above-mentioned method. For example, at least anyone of the resin R2 and the resin R3 does not need to be formed.

Alternatively, the junction layer 30 a does not necessarily need to beformed on the third substrate 10 c, and may be formed on the externalconnection terminal 730 a (the resin R2 and the resin R3).

Next, with reference to FIGS. 12A and 12B, the second substrate 10 b isremoved to expose the first inorganic film 40 a (ST113). The secondsubstrate 10 b is irradiated with a laser light having a predeterminedwavelength from above the second substrate 10 b, for example, and thesecond resin film 313 a is ablated when being heated to evaporation. Asa result, the second substrate 10 b is removed by the power of theablation. Accordingly, as shown in FIG. 12A, the second substrate 10 bis removed on the interface between the second substrate 10 b and thesecond resin film 313 a. By using such a method of laser ablation, thesecond substrate 10 b can be easily removed.

After that, the second resin film 313 a, the adhesive layer 312 a, andthe first resin film 311 a can be removed by a wet etching method, a dryetching method, or the like. Accordingly, the entire temporal junctionlayer 31 a is removed, and thus, it is possible to expose the firstinorganic film 40 a as shown in FIG. 12B.

It should be noted that after the first inorganic film 40 a is exposed,the first inorganic film 40 a on the first electrode 710 a can beremoved to from a connection hole 420 a. In this process, a resist (notshown) on which the pattern of the shape corresponding to the firstelectrode 710 a is formed is formed first, and a dry etching method orthe like via the resist is used similarly to the connection hole 540 a.

Subsequently, with reference to FIG. 12B, the first inorganic film 40 athat has left on the bottom surface 612 a of the first isolation trench61 a is etched to form a second isolation trench 62 a that isolates thefirst inorganic film 40 a for each element 1 a (ST114). In this process,a dry etching method such as an RIE method or a wet etching method isused to form the second isolation trench 62 a.

In this process, the first inorganic film 40 a in an area that faces thebottom surface 612 a of the first isolation trench 61 a is etched first.Next, an area of the second inorganic film 50 a, which is formed in thebottom surface 612 a, is etched similarly. Then, the resin R2, the resinR3, and the junction layer 30 a formed in the area that faces the bottomsurface 612 a are also etched isotropically. Accordingly, the secondisolation trench 62 a having a depth from the first inorganic film 40 ato the third substrate 10 c is formed. The second isolation trench 62 acorresponds to the isolation trench portion 60 of the light emittingelements 1. It should be noted that the above-mentioned etching of thecomponents may be performed under the same conditions or differentconditions.

It should be noted that in this embodiment, the metal layer 53 aincludes the second opening 532 a in the area thereof that faces thebottom surface 612 a, and only the first and second insulating layers 51a and 52 a exist in the area. Accordingly, the area of the reflectionfilm 50 a can be easily etched. Moreover, the resin R3 and the junctionlayer 30 a are etched using the external connection terminal 730 a as amask. Therefore, it is possible to leave only the resin R3 and thejunction layer 30 a that exist in the area facing the externalconnection terminal 730 a as they are.

In this process, the junction layer 30 on the third substrate 10 c(supporting substrate 10), the external connection terminal 730, theluminescent layer 20 covered by the reflection film 50, and the firstinorganic film 40 are isolated for each element 1, and thus, thelight-emitting element wafer 100 is formed.

In the light emitting element 1 according to this embodiment, the firstinorganic film 40 a is formed on the first surface 201 a of theluminescent layer 20 a, and the reflection film 50 a, the externalconnection terminal 730 a, and the junction layer 30 a are formed on thesecond surface 202 b opposite the first surface 201 a. Specifically,crystal growth of the luminescent layer 20 a is caused with a uniformthickness in the plane, and the light emitting element 1 has aconfiguration in which the layers are laminated on the luminescent layer20 a. Thus, the elements 1 in the wafer plane can be formed to have auniform thickness. Accordingly, variation in the thicknesses of theelements 1 in the wafer plane can be suppressed to 10% or less, forexample.

Moreover, the first concavo-convex structure 210 a of the luminescentlayer 20 a is formed right after the crystal growth of the luminescentlayer 20 a is caused. Accordingly, it is possible to form the firstconcavo-convex structure 210 a in a desires shape accurately. Therefore,it is possible to increase the output efficiency, and to control theorientation of light.

Furthermore, because the first inorganic film 40 a functions as anetching stop layer in the process of forming the first isolation trench61 a by a dry etching method or the like, it is possible to form thefirst isolation trench 61 a to have a uniform depth in the plane.Specifically, the first inorganic film 40 a can be configured to beexposed to the bottom surface 612 a of the first isolation trench 61 a.Accordingly, the first inorganic film 40 and the reflection film 50 canbe connected and the second end portion 510 of the reflection film 50and the first end portion 41 of the first inorganic film 40 can belaminated after the elements 1 are formed. Therefore, the elements 1 canbe formed to have a uniform shape, and variation in the heights of theplurality of light emitting elements 1 on the light-emitting elementwafer 100 from the surface 11 can be suppressed to 10% or less, forexample.

Moreover, accordingly, there is no need to provide an etching stop layerfor the luminescent layer 20 a when the first isolation trench 61 a isformed, which can contribute to the increase in the material selectivityof the luminescent layer and the simplification of the productionprocess.

Furthermore, because a dry etching method is used, the area of a waferis increased and an isolation trench can be formed in a uniform shape inthe plane even if the isolation trench is formed to be narrow.

Moreover, in this embodiment, because the wall surface 611 a of thefirst isolation trench 61 a can be formed to be a tapered surface, thereflection film 50 a can be easily formed. In particular, a resinmaterial having low viscosity can be used for the first and secondinsulating layers 51 a and 52 a, and it is possible to easily form thefirst and second insulating layers 51 a and 52 a using a spin coatingmethod or the like.

Furthermore, because the metal layer 53 a can be accurately formed asdescribed above, it is possible to expose the metal layer 53 to the endsurface of the second end portion 510 after the element 1 is formed.Therefore, it is possible to increase the heat radiation property of themetal layer 53 a and to reduce the flaws of the element 1. Moreover,because the metal layer 53 is capable of suppressing the side etching ofthe second end portion 510 when the second isolation trench 62 a isformed, the second isolation trench 62 a can be formed accurately.

The respective light emitting elements 1 on the light-emitting elementwafer 100 formed in this way are mounted on a display apparatus(electronic apparatus) 80, for example.

FIG. 15 is a schematic plan view of the display apparatus 80.Specifically, the light emitting element 1 that emits red light andlight emitting elements 2 and 3 that emit blue light and green lightconstitute a light emitting element unit 81, and a light emittingelement module on which a plurality of light emitting element units 81are arranged is mounted on a substrate 810 of the display apparatus 80.Next, a method of producing the display apparatus 80 and a configurationexample of the display apparatus 80 will be described. It should benoted that in the elements 1, 2, and 3 shown in FIG. 15, configurationssuch as resin that covers them, a wiring, and the like are not shown.

(Method of Producing Display Apparatus)

FIG. 16 is a flowchart of a method of producing the display apparatus 80according to this embodiment, FIG. 17 is a schematic plan view forexplaining the production method, and FIG. 18 are each a schematiccross-sectional view for explaining the production method. To theprocesses shown in FIG. 16, reference numerals continued from ST114shown in FIG. 6 are added. In FIG. 17, only 12 elements 1 are shown fordescription.

With reference to FIG. 17, the outline of the method of producing thedisplay apparatus 80 will be described. The respective light emittingelements 1 on the light-emitting element wafer 100 are transferred to afirst transfer substrate (transfer substrate) 910 first, and arearranged at predetermined intervals larger than the width of theisolation trench portion 60. Furthermore, the element 1 is transferredto a second transfer substrate 920 and is covered by the coating layer922, and a wiring and the like (not shown) are formed. After that, theelement 1 is transferred to the substrate 810 of the electronicapparatus 80 as a light emitting element chip 90 covered by the coatinglayer 922.

As shown in FIG. 18A, the first transfer substrate 910 arranged to facethe first inorganic film 40 of the respective elements 1 of thelight-emitting element wafer 100 is prepared first (ST115). The firsttransfer substrate 910 is formed to have a size such that the elements 1can be arranged at predetermined intervals. The first transfer substrate910 is formed of a glass substrate or a plastic substrate, for example.

On the transfer substrate 910, a first temporal junction layer 911 andan adhesive layer 912 are formed, for example. The first temporaljunction layer 911 is formed on the transfer substrate 910, and mayinclude fluorine resin, silicone resin, a water-soluble adhesive agentsuch as PVA, or polyimide, for example. Moreover, the adhesive layer 912is formed on the first temporal junction layer 911, and may include anultraviolet (UV) curable resin having adhesiveness, thermosetting resin,thermoplastic resin, or the like.

Moreover, the adhesive layer 912 may have an uncured area 912 a and acured area 912 b. Specifically, because the light emitting element 1 tobe transferred is aligned to face the uncured area 912 a, the lightemitting element 1 can be reliably transferred to the adhesive layer 912in the later transfer process. Moreover, in the case where UV curableresin is used for the adhesive layer 912, for example, the cured area912 b can be formed by selectively applying ultraviolet rays only to thearea corresponding to the cured area 912 b to cure the area.Furthermore, in the uncured area 912 a, a concave portion having theshape corresponding to the light emitting element 1 may be formed.

Next, with reference to FIGS. 18A and 18B, the external connectionterminal 730 and the supporting substrate 10 are isolated by the laserablation of the junction layer 30 from the side of the supportingsubstrate (third substrate) 10 of the light-emitting element wafer 100,and the respective elements 1 are transferred to the first transfersubstrate (transfer substrate) 910 (ST116).

In this process, as shown in FIG. 18A, a laser light Lb is applied fromthe side of the supporting substrate 10 to the junction layer 30 of thelight emitting element 1 to be transferred. As the laser, an excimerlaser having a predetermined light emission wavelength or a harmonic YAGlaser can be used, for example. Accordingly, the junction layer 30 isheated to be cured, the adhesiveness is lost, and a part of the resinevaporates, for example. Thus, the junction layer 30 and the externalconnection terminal 730 are explosively removed.

Specifically, the entire element 1 is output in the Z-axis direction andis attached to the adhesive layer 912.

Therefore, as shown in FIG. 18B, the light emitting element 1 istransferred to the adhesive layer 912 that faces the light emittingelement 1.

Then, the uncured area 912 a to which the light emitting element 1 istransferred is cured by the UV irradiation or the like. Accordingly, thelight emitting elements 1 can be reliably joined to the adhesive layer912. Furthermore, a wiring layer 740 may be formed on the externalconnection terminal 730 as necessary.

Moreover, in this process, a light-emitting element wafer 200 includingthe first transfer substrate (supporting substrate) 910 and theplurality of light emitting elements 1 can be formed. Specifically, byperforming the process on the respective desired elements 1, thelight-emitting element wafer 200 in which the plurality of lightemitting elements 1 are arranged on the first transfer substrate 910 canbe formed.

Next, with reference to FIG. 18C, the respective light emitting elements1 are transferred to the second transfer substrate 920, and the firsttransfer substrate 910 is removed (ST117). The second transfer substrate920 typically has almost the same size as the first transfer substrate910, and a second temporal junction layer 921 including fluorine resin,silicone resin, a water-soluble adhesive agent such as PVA, polyimide,or the like is formed thereon. The external connection terminal 730 andthe wiring layer 740 of the respective elements 1 joined to the firsttransfer substrate 910 are joined to the second temporal junction layer921 first. Next, a laser light is applied from above the first transfersubstrate 910 to the first temporal junction layer 911 of the firsttransfer substrate 910, and thus, the first temporal junction layer 911and the adhesive layer 912 are isolated. Accordingly, the entireadhesive layer 912 in which the elements 1 are embedded is transferredto the second temporal junction layer 921.

Furthermore, as shown in FIG. 18C, a third isolation trench 63 may beformed in the adhesive layer 912 between the elements 1 to isolateadhesive layer 912 for each element 1. Accordingly, the coating layer922 formed of the adhesive layer 912, which covers the element 1, isformed. Furthermore, a wiring layer 750 that is connected to the firstelectrode may be formed. Hereinafter, the light emitting element chip 90having a configuration in which the elements 1 and the coating layer 922covering the elements 1 are included will be described. Specifically,the light emitting element chip 90 includes the elements 1, the coatinglayer 922, and the wiring layers 740 and 750.

Then, each light emitting element chip 90 is transferred to thesubstrate 810 of the display apparatus 80 (ST118). As the transfermethod, the above-mentioned laser ablation may be adopted, for example,or an adsorption holder or the like may be used to perform the transfermechanically. The substrate 810 is formed of a wiring substrate on whicha predetermined drive circuit (not shown) is formed.

Moreover, as shown in FIG. 17, the light emitting element chips 90 arearranged on the substrate 810 at predetermined pitches along the X-axisdirection and the Y-axis direction. The predetermined pitch is threetimes or more of the length of the light emitting element chip 90 alongthe X-axis direction and the Y-axis direction. Accordingly, the lightemitting element module 81 can be formed by arranging a light emittingelement chip including the light emitting element 2 that emits bluelight and a light emitting element chip including the light emittingelement 3 that emits green light between the light emitting elementchips 90 including the light emitting elements 1 that emit red light.Moreover, because the light emitting element chips are arranged inspace, a wiring or the like can be formed using the space.

In this way, the display apparatus 80 shown in FIG. 15 is formed.Specifically, the display apparatus 80 includes the substrate 810 onwhich a drive circuit is formed, the plurality of light emittingelements 1 that emit red light, the plurality of light emitting elements2 that emit blue light, the plurality of light emitting elements 3 thatemit green light, and the plurality of light emitting elements 1, 2, and3 are arranged on the substrate 810.

It should be noted that in addition to the process, still anothertransfer substrate may be used to perform the transfer. Specifically,after the process of transferring to the second transfer substrate 920,a process of transferring to a third transfer substrate and a process oftransferring to a fourth transfer substrate may be performed.Accordingly, the respective elements 1 can be transferred at largerintervals, which is advantageous for the formation of a wiring layer orthe production of a display apparatus with a larger area.

It should be noted that in this embodiment, because the metal layer 53of the reflection film 50 is exposed to the second end portion 510, themetal layer 53 is not exposed to the first inorganic film 40.Specifically, even if the wiring layer 750 that is extracted from thefirst electrode 710 to the first inorganic film 40 is formed, twoinsulating layers of the first inorganic film 40 and the firstinsulating layer 51 are sandwiched between the metal layer 53 and thewiring layer 750. Accordingly, it is possible to suppressshort-circuiting between the metal layer 53 and the wiring layer 750,and to reduce the flaws of the element 1.

Moreover, as described above, in this embodiment, it is possible to formthe second isolation trench 62 a accurately in the step of ST114.Specifically, it is possible to suppress the side etching of thejunction layer 30 a etched by using the external connection terminal 730as a mask, and to prevent the position of the center of gravity of thejunction layer 30 a and the luminescent layer 20 a in the XY plane frombeing displaced. Therefore, it is possible to suppress the positionaldisplacement due to the output of the element 1 obliquely to the Z-axisdirection or the falling of the element 1 due to the rotation during theoutput when the laser ablation is performed for each element 1 in thestep of ST116, for example. Therefore, it is possible to transfer theelement to a desired position.

Second Embodiment

FIG. 19 is a cross-sectional view of a main portion showing theconfiguration of a light-emitting element wafer according to a secondembodiment of the present disclosure. In FIG. 19, the same components asthose according to the first embodiment will be denoted by the samereference symbols and a description thereof will be omitted.

A light emitting element 1A of a light-emitting element wafer 100Aaccording to this embodiment is different from the light emittingelement 1 in that a first inorganic film 40A functions also as a firstelectrode 710A. Accordingly, the entire first surface 201 a serves as alight extraction surface, and thus, it is possible to improve the outputefficiency of light emitted from the luminescent layer 20.

The first inorganic film 40A serves also as a first electrode 710Aincluding a transparent conductive material, and includes a transparentconductive material such as ITO. Accordingly, it is possible to ensurethe conductivity while maintaining the translucency of the firstinorganic film 40A. The first inorganic film 40A may have a first endportion 41A formed on the peripheral portion similarly to the firstembodiment, and a second concavo-convex portion (not shown) formedtaking an example from the first concavo-convex portion 210.

The light emitting element 1A may further include an extractionelectrode 711A. The extraction electrode 711A is connected to the firstinorganic film 40A serving as the first electrode 710A, and is capableof extracting the first electrode 710A to the side of the second surface202. Specifically, the extraction electrode 711A is connected to thefirst electrode 710A on the side of the first surface 201, and is formedto above the second surface 202 (second inorganic film 520) via theperipheral surface 203 (third inorganic film 530) of the luminescentlayer 20. The material of the extraction electrode 711A is notparticularly limited, and the extraction electrode 711A includes a metalmaterial such as Al, Au, and Ti, or an alloy or laminated bodycontaining them.

Moreover, the reflection film 50 a may have no second end portion.Accordingly, the extraction electrode 711A can be connected to the firstinorganic film 40A (first electrode 710A) via the first end portion 41A.

An external connection terminal 730A is connected to the secondelectrode 720 via the connection hole 540A. In this embodiment, theexternal connection terminal 730A may be extended from the area locatedimmediately below the second electrode 720 to the isolation trenchportion 60 in one direction, for example. Accordingly, it is possible toprevent the external connection terminal 730A from being brought intocontact with the extraction electrode 711A, and to prevent the problemsuch as short-circuiting from occurring.

In the light emitting element 1A having such a configuration, the firstelectrode 710A including a transparent conductive material is connectedto the extraction electrode 711A including a metal material.Accordingly, it is possible to reduce the change in the connectionresistance between them, and to improve the process margin. Moreover,the connection resistance between the first electrode 710A and thesecond semiconductor layer 22 can be reduced, and also the drivingvoltage can be reduced.

FIGS. 20 to 23 are each a schematic cross-sectional view for explaininga method of producing a light-emitting element wafer 1A. In the methodof producing the light-emitting element wafer 1A according to thisembodiment, the process of forming the first electrode (ST103) and theprocess of forming the first inorganic film (ST104) of the processes inthe method of producing the light-emitting element wafer 1 can beperformed simultaneously. Other processes will be denoted by the samereference symbols as those shown in the flowchart of FIG. 6, andcomponents different from those according to the first embodiment willbe mainly described.

First, a metal organic chemical vapor deposition (MOCVD) method is usedto form the luminescent layer 20 a on the first substrate 10 a (ST101)similarly to the first embodiment. Next, as shown in FIG. 20A, the firstconcavo-convex structure 210 a is formed on the first surface 201 a by,for example, a dry etching method (ST102). In this embodiment, becausethe first concavo-convex structure 210 a can be formed on the entirefirst surface 201 a, a mask may be formed or a mask does not need to beformed when the first concavo-convex structure 210 a is formed.Moreover, the method of forming the first concavo-convex structure 210 ais not limited to a dry etching method or the like, and oxygen ions,blast processing, or the like may be used to rough the first surface 201a.

Next, as shown in FIG. 20B, a first inorganic film 40Aa serving as afirst electrode 710Aa is formed on the first surface 201 a (ST103 andST104). The first inorganic film 40Aa includes, for example, atransparent conductive material such as ITO, and is formed by asputtering method or the like.

Then, by a lift-off method using a mask, a boundary area 610Aa of thefirst inorganic film 40Aa between element areas 1Aa can be removed, andthe first inorganic film 40Aa can be pattern-formed in the shape shownin FIG. 20B.

Next, as shown in FIG. 20C, a second substrate 10Ab is joined to thefirst inorganic film 40Aa (ST105). The second substrate 10Ab may beformed of a sapphire (Al₂O₃) substrate, a silicon (Si) substrate, aquartz substrate, or a glass substrate, for example. Accordingly, thesurface of the second substrate 10Ab is activated by plasma, and thesecond substrate 10Ab can be directly joined to the first inorganic film40Aa by a method such as anodic bonding and room-temperature bonding.Moreover, the second substrate 10Ab can be joined to the first inorganicfilm 40A via a temporal junction layer such as a resin film similarly tothe first embodiment. It should be noted that FIG. 20C shows the statevertically inverted from the state shown in FIG. 20B so that the firstsubstrate 10 a is arranged on the upper side of FIG. 20C.

Next, as shown in FIG. 21A, the first substrate 10 a is removed toexpose the second surface 202 a of the luminescent layer 20 a, which isopposite to the first surface 201 a (ST106) similarly to the firstembodiment. Next, on the second surface 202 a, the second electrode 720a is formed (ST107). Moreover, the second electrode 720 a is used as amask to etch the first contact layer 211 a.

Next, as shown in FIG. 21B, the luminescent layer 20 a is etched fromthe second surface 202 b using the second substrate 10Ab as an etchingstop layer, and a first isolation trench 61Aa that isolates theluminescent layer 20 a for each element (element area) 1Aa is formed(ST108). In this process, an etchant having a high etch selectivityratio with the material of the second substrate 10Ab and the luminescentlayer 20 a is used to perform a dry etching after the mask M1 is formedsimilarly to the first embodiment, and thus, a first isolation trench61Ab can be formed to have a uniform depth in the wafer plane.Accordingly, the second substrate 10Ab is exposed to a bottom surface612Aa of the first isolation trench 61Aa. Furthermore, the mask M1 isremoved after the first isolation trench 61Aa is formed.

Alternatively, similarly to the first embodiment, the first isolationtrench 61Aa may be formed using the first inorganic film 40Aa as anetching stop layer. In this case, an etchant having a high etchselectivity ratio with the first inorganic film 40Aa and the luminescentlayer 20 a can be used to perform a dry etching.

Next, as shown in FIG. 21C, similarly to the first embodiment, areflection film (second inorganic film) 50Aa that covers a wall surface611Aa and the bottom surface 612Aa of the first isolation trench 61Aaand the second surface 202 b is formed (ST109). Although not shown inFIGS. 21C to 23B, the reflection film 50Aa has a laminate structure of afirst insulating layer 51Aa, a metal layer 53Aa, and a second insulatinglayer 52Aa, which are formed in the stated order, as described above.Then, as shown in FIG. 21C, a part of the reflection film 50Aa isremoved to expose the second electrode 720 a (ST110).

Next, as shown in FIG. 22A, on the second surface 202 b, an externalconnection terminal 730Aa that is electrically connected to the secondelectrode 720 a is formed (ST111). In this embodiment, in this process,an extraction electrode 711Aa that is electrically connected to thefirst electrode 710Aa (first inorganic film 40Aa) is formed. Anappropriate method such as a sputtering method, a deposition method, anion plating method, and a plating method is used to form a metal filmhaving a predetermined pattern on the reflection film 50Aa, similarly tothe first embodiment, thereby forming the external connection terminal730Aa and the extraction electrode 711Aa.

Next, with reference to FIG. 22B, on the external connection terminal730Aa and the extraction electrode 711Aa, a third substrate 10Ac isdetachably joined via a junction layer 30Aa (ST112). The junction layer30Aa may include resin having adhesiveness such as polyimide, or resinthat is capable of absorbing a laser light having a predeterminedwavelength, similarly to the first embodiment. Moreover, the thirdsubstrate 10Ac may be formed of a sapphire substrate, for example.

Next, as shown in FIG. 23A, the second substrate 10Ab is removed toexpose the first inorganic film 40Aa (ST113). In this process, thesecond substrate 10Ab can be removed by a dry etching method, a wetetching method, laser ablation in the case of bonding using resin thatis capable of absorbing a laser light having a predetermined wavelength,or the like.

Then, as shown in FIG. 23B, the junction layer 30Aa between elements 1Aais isolated to form a second isolation trench 62Aa (ST114). In thisprocess, a part of the junction layer 30Aa can be removed by a dryetching method or the like. Alternatively, a wet etching method, a laserprocess, or the like can be used to remove the junction layer 30Aa.Moreover, because the first inorganic film 40Aa includes a transparentconductive material such as ITO, the junction layer 30Aa can be etchedusing the first inorganic film 40Aa as a mask. Accordingly, there is noneed to perform the process of forming a mask separately.

By the above-mentioned processes, the light-emitting element wafer 100Aaccording to this embodiment is formed. In this embodiment, the secondsubstrate 10Ab can be joined without a temporal junction layer.Moreover, in the process of forming the first concavo-convex structure210 a (ST102), the process of isolating for each element 1A (ST115), orthe like, a mask does not need to be formed. Therefore, it is possibleto reduce the number of processes, and thus, it is advantageous from aviewpoint of the productivity and cost.

Although embodiments of the present disclosure have been described, theembodiments of the present disclosure are not limited to theabove-mentioned embodiments and various modifications can be madewithout departing from the gist of the present technology.

For example, in the embodiments, the luminescent layer has beendescribed to emit red light. However, the luminescent layer is notlimited thereto, and may emit blue light or green light, for example.For example, in the case where the luminescent layer emits blue light, aGaN material or the like can be used as the material of thesemiconductor, for example.

Furthermore, in the embodiments, the light emitting element has beendescribed to be an LED. However, the light emitting element may includea semiconductor laser or the like. Moreover, the electronic apparatus isnot limited to a display apparatus, and may be a lighting apparatus suchas a car tail lamp, an inspection apparatus on which an LED or asemiconductor laser is mounted, a pickup apparatus that is capable ofwriting to or reading an optical disc, or the like.

Moreover, in the first embodiment, the metal layer is exposed from theend surface of the second end portion. However, the metal layer is notlimited thereto, and does not need to be exposed. In this case, in theprocess of forming the metal layer (ST109-2), with reference to FIG.13B, by forming the resist to have almost the same width (length alongthe width direction between the wall surfaces of the first isolationtrench) as the width of the bottom surface, the second end portion doesnot need to be formed.

Moreover, although the peripheral surface has been described to have atapered surface, the peripheral surface does not limited thereto, andmay be perpendicular to the first and second surfaces, for example.

Furthermore, the reflection film does not have a laminated structure,and may have only one layer. In this case, the reflection film mayinclude an insulating material having a desired reflectance with respectto output light, for example. Moreover, the reflection film may have atwo-layered structure of an insulating layer and a metal layer, and themetal layer may be formed as an extraction electrode of the firstelectrode similarly to the extraction electrode according to the secondembodiment.

Moreover, in the first embodiment, the second substrate 10 b has beendescribed to be joined via the temporal junction layer 31 a. However,the second substrate 10 b may be joined without the temporal junctionlayer 31 a similarly to the second embodiment.

It should be noted that the present disclosure may also take thefollowing configurations.

(1) A light-emitting element wafer, including:

a supporting substrate;

a luminescent layer that is formed of a semiconductor and has a firstsurface and a second surface, the first surface including a firstelectrode, the second surface including a second electrode, the secondsurface being arranged between the supporting substrate and the firstsurface;

a junction layer that joins luminescent layer to the supportingsubstrate and is arranged between the supporting substrate and thesecond surface;

a first inorganic film formed on the first surface;

a second inorganic film formed between the junction layer and the secondsurface;

an isolation trench portion that isolates elements and is formed to havea depth such that the isolation trench portion extends from the firstinorganic film to the supporting substrate; and

a third inorganic film that connects the first inorganic film and thesecond inorganic film.

(2) The light-emitting element wafer according to (1), in which

the first inorganic film has a first end portion formed in parallel withthe first surface, the first end portion projecting to the isolationtrench portion, and

the third inorganic film has a second end portion that takes an examplefrom the first end portion to project to the isolation trench portion.

(3) The light-emitting element wafer according to (2), in which

the second inorganic film and the third inorganic film include a firstinsulating layer, a metal layer, and a second insulating layer, and areformed sequentially, the first insulating layer being formed adjacent tothe luminescent layer, the metal layer being formed on the firstinsulating layer, the second insulating layer being formed on the metallayer.

(4) The light-emitting element wafer according to any one of (1) to (3),in which

the luminescent layer has a first concavo-convex portion formed on thefirst surface, and

the first inorganic film has a second concavo-convex portion formedtaking an example from the first concavo-convex portion.

(5) The light-emitting element wafer according to any one of (1) to (4),in which

the luminescent layer emits red light.

(6) The light-emitting element wafer according to (5), in which

the semiconductor includes at least any one of materials of an AsPcompound semiconductor, an AlGaInP compound semiconductor, and a GaAscompound semiconductor.

(7) The light-emitting element wafer according to any one of (1) to (6),in which

the first inorganic film is the first electrode including a transparentconductive material.

(8) A light emitting element, including:

a luminescent layer that is formed of a semiconductor and has a firstsurface, a second surface, and a peripheral surface, the first surfaceincluding a first electrode, the second surface including a secondelectrode and being opposite to the first surface, the peripheralsurface connecting the first surface and the second surface;

a first inorganic film formed on the first surface;

a second inorganic film formed on the second surface; and

a third inorganic film that is formed to cover the peripheral surfaceand connects the first inorganic film and the second inorganic film.

(9) An electronic apparatus, including:

a substrate on which a drive circuit is formed; and

at least one first semiconductor light-emitting element that is providedon the substrate and includes

-   -   a luminescent layer that is formed of a semiconductor and has a        first surface, a second surface, and a peripheral surface, the        first surface including a first electrode connected to the drive        circuit, the second surface including a second electrode, the        second surface being disposed between the substrate and the        first surface, the second electrode being connected to the drive        circuit, the peripheral surface connecting the first surface and        the second surface,    -   a first inorganic film formed on the first surface,    -   a second inorganic film formed between the luminescent layer and        the second surface,    -   a third inorganic film that is formed to cover that peripheral        surface and connects the first inorganic film and the second        inorganic film.        (10) The electronic apparatus according to (9), further        including:

a plurality of second semiconductor light-emitting elements configuredto emit blue light; and

a plurality of third semiconductor light-emitting elements configured toemit green light, in which

the at least one first semiconductor light-emitting element includes aplurality of first semiconductor light-emitting element configured toemit red light, and the plurality of first, second, and thirdsemiconductor light-emitting elements are arranged on the substrate.

(11) A method of producing a light-emitting element wafer, including:

forming a luminescent layer having a laminated structure in which asemiconductor is laminated on a first substrate;

forming a first inorganic film on a first surface of the luminescentlayer;

removing the first substrate to expose a second surface of theluminescent layer, the second surface being opposite to the firstsurface;

etching the luminescent layer from the second surface with the firstinorganic film being an etching stop layer to form a first isolationtrench that isolates the luminescent layer for each element; and

forming a second inorganic film that covers the second surface and awall surface and a bottom surface of the first isolation trench.

(12) The method of producing a light-emitting element wafer according to(11), in which

the forming of the first isolation trench includes etching theluminescent layer by a dry etching method.

(13) The method of producing a light-emitting element wafer according to(12), in which

the forming of the first isolation trench includes forming the firstisolation trench so that a cross-sectional area of the luminescent layerfor each element is gradually increased from the second surface to thefirst surface.

(14) The method of producing a light-emitting element wafer according toany one of (11) to (13), in which

the forming of the second inorganic film includes

-   -   forming a first insulating layer on the second surface and the        wall surface and the bottom surface of the first isolation        trench,    -   forming a metal layer on the first insulating layer, and    -   forming a second insulating layer on the metal layer.        (15) The method of producing a light-emitting element wafer        according to any one of (11) to (14), further including

forming a first concavo-convex structure on the first surface before theforming of the first inorganic film and after the forming of theluminescent layer.

(16) The method of producing a light-emitting element wafer according to(15), in which

the forming of the first inorganic film includes taking an example fromthe first concavo-convex structure to form a second concavo-convexstructure.

(17) The method of producing a light-emitting element wafer according to(11) to (16), further including

detachably joining the second substrate to the first inorganic film viaa tentative a tentative junction layer before the exposure of the secondsurface and after the forming of the first inorganic film.

(18) The method of producing a light-emitting element wafer according to(17), further including:

forming an electrode for each device on the second surface before theforming of the first isolation trench after the exposure of the secondsurface;

removing a part of the second inorganic film to expose the electrodeafter the forming of the second inorganic film;

forming an external connection terminal that is electrically connectedto the electrode on the second surface; and

detachably joining a third substrate to the external connection terminalvia the junction layer.

(19) The method of producing a light-emitting element wafer according to(18), further including:

removing the second substrate to expose the first inorganic film; and

etching the first inorganic film remained on the bottom surface of thefirst isolation trench to form a second isolation trench that isolatesthe first inorganic film for each element, after the joining of thethird substrate.

(20) The method of producing a light-emitting element wafer according to(19), further including:

preparing a transfer substrate arranged to face the first inorganicfilm; and

isolating the external connection terminal from the third substrate bylaser ablation of the junction layer to transfer each element on thetransfer substrate, after the forming of the second isolation trench.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A light emitting element, comprising: aluminescent layer that has oppositely facing first and second surfaces,the first surface having a first concavo-convex structure; a firstinorganic film on the first surface of the luminescent layer, the firstinorganic film having a second concavo-convex structure with a shapeconforming to a shape of the first concavo-convex structure; a secondinorganic film on the second surface of the luminescent layer; a firstelectrode for the light-emitting element on the first surface, the firstelectrode being exposed through and in addition to the first inorganicfilm or being the first inorganic layer film itself; a second electrodefor the light-emitting element on the second surface of the luminescentlayer, the second electrode being exposed through the second inorganicfilm; and an external connection terminal that is electrically connectedto the second electrode, wherein, the second inorganic film includes (a)a first insulating layer on the second surface of the luminescent layer,(b) a metal layer on the first insulating layer, and (c) a secondinsulating layer on the metal layer.
 2. The light emitting element ofclaim 1, wherein a cross-sectional area of the luminescent layer for thelight emitting element continuously increases from the second surface tothe first surface.
 3. The light emitting element of claim 1, wherein thefirst electrode is in addition to the first inorganic film.
 4. Anelectronic apparatus, comprising: a substrate; and a light-emittingelement as claimed in claim 1, the light-emitting element beingconfigured to emit red light.
 5. The electronic apparatus of claim 4,further comprising: (a) a connection hole in the second inorganic filmthat exposes the second electrode, the second electrode being within theconnection hole, (b) a third inorganic film that covers a peripheralsurface of the light-emitting element and connects the first inorganicfilm and the second inorganic film, (c) a junction layer joining thelight emitting element to the substrate, and (d) a conductive connectionlayer between the junction layer and the second inorganic film, theconductive connection layer being connected to the second electrode. 6.The electronic apparatus of claim 4, wherein the first inorganic film ofthe light emitting element is made of SiN, SiO₂, TiN, or TiO₂.
 7. Theelectronic apparatus of claim 4, wherein the second inorganic film ofthe light-emitting element extends to and covers a peripheral surface ofthe light-emitting element as a third inorganic film that connects thefirst inorganic film and the second inorganic film.
 8. The electronicapparatus of claim 4, wherein the luminescent layer of the lightemitting element comprises an active layer between two cladding layers.9. The electronic apparatus of claim 8, wherein the first concavo-convexstructure of the light-emitting element is provided in a surface of oneof the cladding layers.
 10. The electronic apparatus of claim 9, whereinthe light emitting element comprises a contact layer on the one claddinglayer, the first concavo-convex structure being provided in the contactlayer and the surface of the one cladding layer.
 11. The electronicapparatus of claim 4, wherein the first electrode is in addition to thefirst inorganic film.
 12. The electronic apparatus of claim 4, whereinthe first inorganic film serves as the first electrode.
 13. Theelectronic apparatus of claim 4, wherein a cross-sectional area of theluminescent layer for the light emitting element continuously increasesfrom the second surface to the first surface.
 14. An electronicapparatus, comprising: a substrate; a first light-emitting element asclaimed in claim 1, but configured to emit red light; a secondsemiconductor light-emitting element as claimed in claim 1, butconfigured to emit blue light; and a third semiconductor light-emittingelement as claimed in claim 1, but configured to emit green light,wherein, the first, second, and third semiconductor light-emittingelements are arranged on the substrate and are isolated from each other.15. The electronic apparatus of claim 14, wherein, for each of thefirst, second, and third light emitting elements, the first inorganicfilm of the light emitting element is made of SiN, SiO₂, TiN, or TiO₂.16. The electronic apparatus of claim 14, wherein, for each of thefirst, second, and third light emitting elements, the second inorganicfilm of the light-emitting element extends to and covers a peripheralsurface of the light-emitting element as a third inorganic film thatconnects the first inorganic film and the second inorganic film.
 17. Theelectronic apparatus of claim 14, wherein, for each of the first,second, and third light emitting elements, the luminescent layer of thelight emitting element comprises an active layer between two claddinglayers.
 18. The electronic apparatus of claim 17, wherein, for each ofthe first, second, and third light emitting elements, the firstconcavo-convex structure of the light-emitting element is provided in asurface of one of the cladding layers.
 19. The electronic apparatus ofclaim 18, wherein, for each of the first, second, and third lightemitting elements, the light emitting element comprises a contact layeron the one cladding layer, the first concavo-convex structure beingprovided in the contact layer and the surface of the one cladding layer.20. The electronic apparatus of claim 14, wherein, for each of thefirst, second, and third light emitting elements, the first electrode isin addition to the first inorganic film.
 21. The electronic apparatus ofclaim 14, wherein, for each of the first, second, and third lightemitting elements, the first inorganic film serves as the firstelectrode.
 22. The electronic apparatus of claim 14, wherein, for eachof the first, second, and third light emitting elements, across-sectional area of the luminescent layer for the light emittingelement continuously increases from the second surface to the firstsurface.
 23. The semiconductor light-emitting element of claim 1,wherein the first inorganic film is made of SiN, SiO₂, TiN, or TiO₂. 24.The semiconductor light-emitting element of claim 1, wherein the secondinorganic film extends to and covers a peripheral surface of thelight-emitting element as a third inorganic film that connects the firstinorganic film and the second inorganic film.
 25. The semiconductorlight-emitting element of claim 1, wherein the luminescent layercomprises an active layer between two cladding layers.
 26. Thesemiconductor light-emitting element of claim 25, wherein the firstconcavo-convex structure is provided in a surface of one of the claddinglayers.
 27. The semiconductor light-emitting element of claim 26,comprising a contact layer on the one cladding layer, the firstconcavo-convex structure being provided in the contact layer and thesurface of the one cladding layer.
 28. The semiconductor light-emittingelement of claim 1, wherein the first inorganic film serves as the firstelectrode.